The house can't burn down or even slightly up because we've already seen the state of it in the flash forwards. It's derelict, cleaned out and vandalized buti didn't see any prominent burn marks.
I just caught up today with the show and i'm simply speechless.. it's been said already here in this thread but the way the show makes you repeatedly root for Walt to come through in all his endeavours is just brilliant.
Up until Jane's death it was also easy to do so.. he only killed off scum (especially those two drug dealers who killed the little kid they trained to be their dealer) but even after it you still had moments of "Go Walt! Show them evil guys!" but deep down you knew it was wrong.
I honestly can't imagine how this can end.. it will be very violent (how can it not be with an ex-chemistry teacher lugging around an M60 machine gun in his trunk) but given the vibe of the show i'm pretty sure i'll be speechless again.
About Hank.. i think he's close to losing it. He knows his job is done any way he slices it. When it comes out that Walter White is Heisenberg (and it will for sure as evidenced by the flash forward) his career will be over much like his former boss who had even less connections to Gustavo Frings. However it might be that Hank simply snaps.. he's a very emotional guy prone to wild mood swings and that's not good if you're vindictive, armed and out for revenge. I don't see this ending well for Hank at all.